Frequency of the atypical aldehyde dehydrogenase-2 gene (ALDH2(2)) in Japanese and Caucasians.

All Caucasians have two major aldehyde dehydrogenase isozymes--i.e., the cytosolic ALDH1 and the mitochondrial ALDH2-while approximately 50% of Orientals are atypical and lack the catalytically active ALDH2 in their tissues. The atypical ALDH2(2) gene has a nucleotide base change and produces the defective ALDH2(2) protein, which has a Glu----Lys substitution at the 14th position from the COOH-terminal (Yoshida et al. 1984; Hsu et al. 1985). With the use of a pair of synthetic oligonucleotides-one complementary to the usual ALDH1(2) and the other complementary to the atypical ALDH2(2)-genotypes of 49 unrelated Japanese individuals and 12 Caucasians were determined. The frequency of the atypical ALDH2(2) allele was found to be .35 in the Japanese samples examined. The atypical ALDH2(2) gene was not found in the Caucasians.